Tip: alternative for NR==FNR in awk


 
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# 8  
Old 08-01-2014
Thanks Don, I though that ARGV is GNUmagic.
So my first example should be improved like this
Code:
awk '
BEGIN {
for (i=1; i<ARGC; i++) if (ARGV[i]!~"=") {f1=ARGV[i]; break}
}
FILENAME==f1 {A[$1]; next}
($1 in A)
' file1 file2

And works nicely with shell wildcards like file*!
BTW most awk versions want if (... ~ "=") instead of if (... ~ /=/), even outside a {block}.
They have a problem to parse the characters ( ) = within / / but not within " ".

Last edited by MadeInGermany; 08-01-2014 at 05:29 PM.. Reason: Corrected my observation
This User Gave Thanks to MadeInGermany For This Post:
# 9  
Old 08-01-2014
Quote:
Originally Posted by MadeInGermany
Thanks Don,
... ... ...
BTW most awk versions want if (... ~ "="). While all accept (... ~ /=/) outside a {block}
Thanks for the warning.

The standards say that the right hand operand of the ~ and !~ operators can always be a string containing an ERE or an ERE token (i.e., /ERE/). But, if there is an ambiguity as to whether a / is a division operator or part of an ERE token, awk is supposed to assume it is a division operator. In a simple if statement like this, there shouldn't be any ambiguity.
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